MANILA —
The Philippines says a plan by China's Hainan province to stop and search foreign ships deemed to be illegally in the South China Sea is a "gross violation" of international law and hampers freedom of navigation.

The Philippine Department of Foreign Affairs is demanding clarification from China over the plans. The department said in a statement it is "especially concerned" by media reports that starting next year, Hainan police will have authority to board, search and possibly seize foreign ships they determine have illegally entered Chinese-claimed waters .

The statement says that since China claims practically the entire sea, this sort of action would pose a "direct threat to the entire international community" and violates the U.N. Convention on the Law of the Sea.

Philippine Congressman Walden Bello, who has been vocal in opposing China's claim, calls it a "flagrant violation of international law."

"Basically this is one more step in terms of the really, very, very dangerous escalation- this is a dangerous escalation- of the illegal claim of the Chinese government," said Bello.

Mayor Eugenio Bito-onon of the Kalayaan Group of Islands, which are the Philippines' claimed parts in the Spratlys, also calls the move dangerous. While Hainan province is two day's boat ride northeast, he is skittish about such a plan in waters being shared by several countries.

"I'm apprehensive because if they do that then that would be for the first time, I think, very contentious because it would already impinge on our freedom of navigation," said Bito-onon.

Along with the Philippines and China, Vietnam, Malaysia, Taiwan and Brunei all have claims in the sea, which has one of the world's most heavily traversed shipping routes. It is also a rich fishing ground and is believed to hold vast fossil fuel reserves.

On Friday, the secretary-general of the 10-member Association of Southeast Asian Nations (ASEAN) said the Chinese action raises the level of concern and great anxiety.

Ely Ratner, Asia fellow with the Center for a New American Security, says the plan is worrisome, counter-productive on China's part and may be hard to enforce.

"They end up leading to serious pushback and diplomatic rancor from the rest of the region," said Ratner.

China's official news agency quoted a Chinese foreign ministry spokesman Friday as saying the country gives great importance to freedom of navigation.